Diagnostic decision support in ophthalmology

Isabel is a Web-based, diagnostic decision support tool designed to provide a differential diagnosis of a patient's condition for interpretation by a qualified health-care professional. We investigated the accuracy of the Isabel system in ophthalmic primary care. A total of 100 case histories were prospectively collected from ophthalmic primary care clinic records. The patient demographics and clinical features of each case were then entered into the Isabel system, and the results generated by the decision support tool for each case were compared with the diagnosis reached by the ophthalmic team. Of the 100 cases in the dataset, there was no matching diagnosis in the first 2 pages of Isabel results in 40 cases. Of the 60 cases in which there was a matching diagnosis on the first 2 pages of results, 31 had a >50% match between the terms of the query and the Isabel diagnosis reminder system's database. It remains to be established whether this is high enough to be clinically useful in a practice setting. Inclusion of specific ophthalmic knowledge would probably improve the accuracy of the Isabel clinical diagnostic decision support system.

Ethnic disparities in risk of cardiovascular disease, end-stage renal disease and all-cause mortality: a prospective study among Asian people with Type 2 diabetes

AIM

To study prospectively the ethnic-specific risks of cardiovascular disease, end-stage renal disease and all-cause mortality in patients with Type 2 diabetes mellitus among native Asian subpopulations.

METHODS

A total of 2337 subjects with Type 2 diabetes (70% Chinese, 17% Malay and 13% Asian Indian) were followed for a median of 4.0 years. Time-to-event analysis was used to study the association of ethnicity with adverse outcomes.

RESULTS

Age- and gender-adjusted hazard ratios for cardiovascular disease in ethnic Malay and Asian Indian subjects were 2.01 (1.40-2.88; P<0.0001) and 1.60 (1.07-2.41; P=0.022) as compared with Chinese subjects. Adjustment for conventional cardiovascular disease risk factors, including HbA1c , blood pressure and lipid profile, slightly attenuated the hazards in Malay (1.82, 1.23-2.71; P=0.003) and Asian Indian subjects (1.47, 0.95-2.30; P=0.086); However, further adjustment for baseline renal function (estimated GFR) and albuminuria weakened the cardiovascular disease risks in Malay (1.48, 0.98-2.26; P=0.065) but strengthened that in Asian Indian subjects (1.81, 1.14-2.87; P=0.012). Competing-risk regression showed that the age- and gender-adjusted sub-distribution hazard ratio for end-stage renal disease was 1.87 (1.27-2.73; P=0.001) in Malay and 0.39 (0.18-0.83; P=0.015) in Asian Indian subjects. Notably, the difference in end-stage renal disease risk among the three ethnic groups was abolished after further adjustment for baseline estimated GFR and albuminuria. There was no significant difference in risk of all-cause mortality among the three ethnic groups.

CONCLUSIONS

Risks of cardiovascular and end-stage renal diseases in native Asian subjects with Type 2 diabetes vary substantially among different ethnic groups. Differences in prevalence of diabetic kidney disease may partially explain the ethnic disparities.

Iris concavity, corneal biomechanics, and their correlations with ocular biometry in a cohort of 10- to 12-year-old UK school boys: baseline data

PURPOSE

Pigment dispersion syndrome is associated with iris concavity. This study investigated the prevalence of iris concavity, defined as a measurement of ≤-0.1 mm, in a cohort of 10- to 12-year-old boys, and explored the relationship between iris curvature and anterior segment biometry. Associations with corneal biomechanical parameters also were explored.

METHODS

A cohort of school boys (n = 96) was recruited from a local school. Anterior segment optical coherence tomography (AS-OCT) was performed under accommodative and nonaccommodative conditions, and iris curvature quantified. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with the ocular response analyzer (ORA). Noncontact axial biometry was performed using laser interferometry.

RESULTS

The prevalence of iris concavity was 24% on distance fixation, increasing to 65% on accommodation. Variables significantly associated with nonaccommodating iris curvature were lens vault (P = 0.02) and mean keratometry (P = 0.02). For both variables acting jointly, R(2) = 0.30. Variables associated significantly with accommodating iris curvature were anterior chamber depth (P = 0.009), lens vault (P = 0.049), and mean scleral spur angle (P < 0.0001). For these three variables acting jointly, R(2) = 0.33. Significant association was found between CH and spur-to-spur distance (R(2) = 0.07, P = 0.025).

CONCLUSIONS

Iris concavity was a common finding in this cohort and related to anterior segment biometric parameters. Further work is required to clarify whether anatomical differences exist between iris concavity seen in the adolescent eye and that found in adults with pigment dispersion syndrome.

Energy requirements for maintenance and growth of entire male Bali cattle in East Timor

The metabolisable energy (ME) requirements for maintenance and growth of entire male Bali cattle (Bos javanicus) were determined by regressing liveweight change on ME intake. Cattle were fed either a diet (DM basis) of 52.5% urea-treated rice straw plus 47.5% fresh leucaena forage (Expt 1), or fresh leucaena forage alone (Expt 2). In each experiment, liveweight change and feed intake were measured over 4 weeks, after a 1-week introductory period, and feed constituent digestibilities were measured during the final week. In Expt 1, 10 bulls between 1.5 and 3 years of age and weighing 123.7 ± 11.79 kg (mean ± s.d.) were allocated to DM intakes estimated to provide 0.75, 1.0, 1.25, 1.5, 1.75, or 2.0 times the estimated ME requirement for maintenance (based on calculations made from published CSIRO equations for tropical cattle species other than B. javanicus), with either one or two bulls per treatment. In Expt 2, the bulls were given treatments estimated to provide 0.85, 1.0, 1.4, 1.8, or 2.2 times the ME requirement for maintenance, with two bulls allocated to each treatment. The measured ME requirements for maintenance were 0.42 ± 0.369 and 0.40 ± 0.153 MJ/kg LW0.75.day (coefficient ± standard error, Expts 1 and 2, respectively). The ME requirement for ‘production’ (i.e. positive liveweight change of male Bali cattle under the specific conditions of the experiment) was calculated to be 39.2 MJ/kg liveweight gain in Expt 2. The calculated efficiency of use of dietary ME for production in Expt 2, was 0.34

Genotype-phenotype analysis of SNPs associated with primary angle closure glaucoma (rs1015213, rs3753841 and rs11024102) and ocular biometry in the EPIC-Norfolk Eye Study

AIMS

To investigate if the single nucleotide polymorphisms rs3753841, rs1015213 and rs11024102, recently implicated in the development of acute primary angle closure or primary angle closure glaucoma, are associated with ocular biometric characteristics of British adults in the European Prospective Investigation of Cancer-Norfolk eye study.

METHODS

Genotyping data on rs1015213 (between PCMTD1 and ST18), rs11024102 (at PLEKHA7) and rs3753841 (at COL11A1) were available on 3268 participants. Direct genotypic data was available for rs1015213 and rs3753841. Data was imputed for rs11024102. Ocular biometric data was available on 1137 participants who attended the third European Prospective Investigation of Cancer health examination and 988 (87%) of these participants had no previous cataract surgery either eye. Axial length (AL), anterior chamber depth (ACD) and corneal keratometry were measured by using the Zeiss IOLMaster.

RESULTS

Presence of at least one A allele (AG or AA genotype) for rs1015213 was associated with a shallower ACD (-0.07 mm, 95% CI -0.01 to -0.14 mm, p=0.028) after adjusting for age and sex (both p≤0.001). There was no association with AL or corneal keratometry for rs1015213 genotypes. AL, ACD and keratometry were not associated with rs3753841 or rs11024102 genotypes including after adjusting for age and sex.

CONCLUSIONS

This study suggests that primary angle closure glaucoma susceptibility at the PCMTD1-ST18 locus may be partly explained by an association between rs1015213 and ACD in European populations. This effect is equivalent to almost 20% of the SD of the mean ACD of phakic individuals in this cohort. We were not able to identify any association between rs3753841 or rs11024102 and ocular biometry.

Functional characterization of a novel c.614-622del rhodopsin mutation in a French pedigree with retinitis pigmentosa

PURPOSE

To identify and functionally characterize the mutation responsible for autosomal dominant retinitis pigmentosa (adRP) in a large, six-generation French family.

METHODS

Twenty individuals from this family participated in the genetic investigation. Six affected and 14 unaffected individuals from three-generations were available for linkage analysis using microsatellite markers flanking the rhodopsin (RHO) gene. A two-point logarithm of odds (LOD) score calculation was undertaken using GENEMARKER and MLINK software. Sanger sequencing of RHO was performed. Cellular localization of the mutant protein was performed by transforming SK-N-SH cells with pEGFP-N1-Rho, pEGFP-N1-Rho(P23H), and pEGFP-N1-Rho(c.614-622del).

RESULTS

The proband had nyctalopia, visual field constriction, peripheral bone spicule pigmentation of the fundus, central acuity (6/24 RE; 6/12 LE) at 55 years of age. Linkage analysis of this family suggested RHO as a possible candidate since the flanking marker D3S1292 yielded a LOD score of 2.43 at θ=0. Cloning of an exon 3 PCR product and direct sequencing of single clones identified a novel deletion in the third exon of RHO, c.614-622del (p.Y206-F208del). The deleted mutant protein localized to the endoplasmic reticulum and formed inclusion bodies.

CONCLUSIONS

This novel deletion in exon 3 of the RHO gene, c.614-622del results in a classical form of adRP in a multi-generation French family. Protein expression analyses confirmed that the deletion led to protein misfolding and suggest this is a class II mutation, similar to P23H, the most common class II mutation seen in North America.

Autosomal dominant Best disease with an unusual electrooculographic light rise and risk of angle-closure glaucoma: a clinical and molecular genetic study

PURPOSE

To describe the clinical and molecular characteristics of two families with autosomal dominant Best disease and atypical electrooculography (EOG).

METHODS

Four affected individuals from two families were ascertained. Detailed ophthalmic examinations, refraction, and biometry (anterior chamber depth [ACD] and axial length [AL]), gonioscopy, optical coherence tomography of the anterior segment and retina, retinal imaging, and electrophysiological assessment were performed. Arden ratios from EOG testing were calculated by direct measurement of the light peak to dark trough amplitudes. Mutations in bestrophin 1 (BEST1) were identified by bidirectional Sanger sequencing. In family 1, segregation of BEST1 alleles was performed by assaying four microsatellite markers (D11S935, D11S4102, D11S987, and D11S4162) that flank BEST1.

RESULTS

The proband from family 1 (three of four siblings affected with Best disease) was 42 years old with bilateral macular vitelliform lesions, advanced angle closure glaucoma (ACG), a normal electroretinogram, and no EOG light rise. Her 44-year-old brother had similar fundus appearances and an EOG light rise of 170%. Their 48-year-old sister had a normal left fundus, whereas the right fundus showed a vitelliform lesion and subretinal thickening. There was no EOG light rise detectable from either eye. Mutation analysis of BEST1 showed all affected siblings to be heterozygous for a missense mutation, c.914T>C, p.Phe305Ser. Their unaffected sister had an EOG light rise of 200%, a normal fundus appearance, and did not harbor the BEST1 mutation. Haplotype analysis of family 1 showed that the affected brother with the 170% EOG light rise had inherited the same nondiseased parental BEST1 allele as his unaffected sister. The other two affected sisters with undetectable EOG light rises shared a different nondiseased parental BEST1 allele. An unrelated 53-year-old female carrying the same c.914T>C, p.Phe305Ser mutation showed typical features of Best disease and an EOG light rise of 180%. All four siblings from family 1 had shorter axial biometry (ACD range 2.06-2.74 mm; AL range 20.46-22.60 mm) than the normal population, contributing to their risk of ACG development. Proband 2 had deeper ACDs (2.83 mm OD and 2.85 mm OS), but similar ALs (21.52 mm OD and 21.42 mm OS) compared to family 1. She had no gonioscopic evidence of angle closure.

CONCLUSIONS

A near normal EOG light rise is uncommon in molecularly confirmed Best disease, and in the present report is associated with the same mutation in two families, suggesting a specific role for this amino acid in the retinal pigment epithelium dysfunction associated with this disorder. Haplotype analysis in family 1 was consistent with an effect of the nondisease allele in mediating the presence of an EOG light rise. Clinical assessment of ACG risk is recommended for BEST1 mutation carriers and their first degree relatives.

A synonymous codon variant in two patients with autosomal recessive bestrophinopathy alters in vitro splicing of BEST1

PURPOSE

Autosomal recessive bestrophinopathy (ARB) is a newly defined retinal dystrophy caused by biallelic mutations in bestrophin-1 (BEST1) and is hypothesized to represent the null bestrophin-1 phenotype in humans. The aim was to determine whether a synonymous BEST1 variant, c.102C>T, identified in two unrelated ARB patients, alters pre-mRNA splicing of the gene. Additionally a detailed phenotypic characterization of this distinctive condition is presented for both patients.

METHODS

BEST1 was analyzed by direct sequencing. Patients underwent standard ophthalmic assessment. In silico and in vitro analysis using a minigene system was performed to assess whether a synonymous variant identified, c.102C>T p.Gly34Gly, alters pre-mRNA splicing of BEST1.

RESULTS

Both ARB patients harbored either proven (patient 1; c.102C>T p.Gly34Gly and c.572T>C p.Leu191Pro) or presumed (patient 2; c.102C>T p.Gly34Gly and c.1470_1471delCA, p.His490GlnfsX24) biallelic mutations in BEST1 and were found to have phenotypes consistent with ARB. In vitro analysis of the synonymous variant, c.102C>T p.Gly34Gly, demonstrated it to introduce a cryptic splice donor site 52 nucleotides upstream of the actual splice donor site.

CONCLUSIONS

The novel BEST1 variant identified, c.102C>T p.Gly34Gly, alters pre-mRNA splicing in vitro and is potentially pathogenic. In vivo this splicing variant is predicted to lead to the production of an mRNA transcript with a premature termination codon (p.Glu35TrpfsX11) that is predicted to be degraded by NMD.

Pharmacological and environmental factors in primary angle-closure glaucoma

INTRODUCTION OR BACKGROUND

A large number of drug classes have now been reported to provoke angle closure in high-risk individuals. The mechanism of action can be generalized into three main categories: sympathomimetic, parasympatholytic and idiosyndratic reactions.

SOURCES OF DATA

This review of the ophthalmic literature provides a clinical summary of primary angle-closure glaucoma (PACG) and its management.

AREAS OF AGREEMENT

External stimuli (pharmacological and environmental) may induce acute, and more often, asymptomatic angle closure, which carries a significant risk of glaucoma.

GROWING POINTS

Whenever in doubt, patients at risk of PACG who are starting on drug therapy known to provoke angle closure or aggravate the condition should be referred for detailed gonioscopic examination of the anterior chamber by an ophthalmologist. AREAS FOR DEVELOPING RESEARCH: The use of new imaging methods such as anterior segment optical coherence tomography to assess the presence or risk of angle closure is gaining popularity, and may offer a more rapid method of identifying people who are at risk of sight loss from angle-closure glaucoma precipitated by non-ophthalmological medication.

Mortality among tuberculosis patients on treatment in Singapore

OBJECTIVE

To identify the risk factors associated with mortality among tuberculosis (TB) patients on treatment in Singapore.

DESIGN

A retrospective cohort study of 7433 TB patients notified and started on TB treatment from 2000 to 2006 was conducted. Cox regression analysis was used to determine independent risk factors for mortality.

RESULTS

Of 7433 patients who started TB treatment between 2000 and 2006, there were 884 deaths (11.9%) from any cause. Older age, male sex, being in a long-term care facility, having comorbidity, absence of cough, more than one site of TB, bacteriologically confirmed laboratory results, resistance to at least isoniazid (INH) and rifampicin (RMP) and absence of cavity were strongly associated with all-cause mortality among TB patients. A total of 203 patients (2.7%) died of TB. Risk factors for death due to TB were older age, male sex, Malay ethnicity, being in a long-term care facility, absence of cough, more than one site of TB, bacteriologically confirmed laboratory results and resistance to at least INH and RMP or to at least INH but not RMP.

CONCLUSION

It is important to identify TB patients with risk factors related to mortality so that appropriate and timely interventions can be instituted to prevent deaths among TB patients.

Is measurement of adult height useful in screening for primary angle closure?

BACKGROUND

Adult height is independently related to ocular dimensions and shorter people have shorter globes and shallower anterior chambers. We investigated the relationship between adult height and angle dimensions to explore measuring height as a possible screening test for angle closure.

METHODS

A population-based, cross-sectional survey of adult Chinese living in the Tanjong Pagar district, Singapore was conducted. Anterior chamber depth, gonioscopic angle width and height were assessed using standardized protocols.

RESULTS

Data were available for 996 persons. Shorter people had shallower anterior chamber depth (2.35 mm for persons <144 cm vs 2.72 mm for persons >170 cm, P=0.008) and smaller gonioscopic angles (22 degrees for <144 cm vs 30 degrees for >170 cm, P=0.079). After controlling for age and gender, adult height was significantly related to anterior chamber depth (P=0.008) but not significantly related to gonioscopic angle width (P=0.079). Female sex and age > or = 50 years used together correctly identified 45/66 (68.2%) individuals with an occludable angle (sensitivity 68.2%, specificity 61.3%). Fewer people, 41/66 (62.1%), were correctly identified when height <160 cm was added to female sex and age 50 > or = years (sensitivity was 62.1% and specificity was 64.7%).

CONCLUSIONS

Shorter adult height is significantly associated with a shallower anterior chamber depth, but the addition of height contributed little to demographics (age and gender) as the preliminary screening criteria to identify individuals at risk of an occludable angle.

A national study of the epidemiology of pneumococcal disease among hospitalised patients in Singapore: 1995 to 2004

INTRODUCTION

Infections with Streptococcus pneumoniae cause significant morbidity and mortality. In this study, we describe the epidemiology of pneumococcal disease based on hospitalisation rates for all age groups in Singapore. This is important for evaluating prevention and control strategies of pneumococcal disease.

METHODS

We conducted a retrospective study of hospitalisation cases admitted to all public and private hospitals from 1995 to 2004. 4,275 hospitalisation records were extracted, based on the International Classification of Diseases, Ninth Revision (ICD-9) codes for pneumococcal disease. We analysed the demographics, type of pneumococcal disease, length of stay and case fatality of these cases.

RESULTS

Our study showed that the mean annual hospitalisation rate for pneumococcal disease was 10.9 per 100,000 population from 1995 to 2004. The mean annual hospitalisation rate was highest in the young and the elderly.

CONCLUSION

Baseline information on the epidemiology of pneumococcal disease is important for the formulation and evaluation of a national prevention and control programme.

Five-year experience of the 2-incision push-pull technique for anterior and posterior capsulorrhexis in pediatric cataract surgery

PURPOSE

To describe the authors' 5-year experience of the 2-incision push-pull (TIPP) technique for pediatric anterior and posterior capsulorrhexis formation.

DESIGN

Retrospective descriptive study over a 5-year period.

PARTICIPANTS

A total of 84 eyes of 63 patients who had undergone cataract surgery in 1 center.

METHODS

Retrospective review of all consecutive patients who underwent pediatric cataract extraction with planned intraocular lens implantation and TIPP rhexis between January, 1999, and August, 2004. Any lost capsulorrhexis, or capsular tears at any stage of the operation, and the relation of optic size to anterior capsulorrhexis size were noted.

MAIN OUTCOME MEASURES

Complications during TIPP rhexis formation and any late complications at last visit.

RESULTS

The mean age at operation was 70.21 months (range, 4 weeks-18 years). All eyes had anterior TIPP rhexis; 41 eyes also had posterior TIPP rhexis, and there were no anterior or posterior capsulorrhexis loss or tears while performing the technique. In no patient in whom TIPP rhexis was performed for the posterior capsule was there an inadvertent vitreous loss during rhexis formation. All eyes had anterior rhexis diameters that were smaller than the optic diameter (5.5-6.0 mm), approximately 4 to 4.5 mm in diameter. Four capsular tears were reported; 1 tear occurred during irrigation and aspiration and the others during rigid lens insertion. No late complications were noted.

CONCLUSIONS

Our 5-year experience with the TIPP rhexis in pediatric cataract surgery has shown this to be a reliable method for producing a consistent-size capsulorrhexis opening in both anterior and posterior capsulorrhexis.

Effects of sampling standardization on estimates of Phanerozoic marine diversification

Global diversity curves reflect more than just the number of taxa that have existed through time: they also mirror variation in the nature of the fossil record and the way the record is reported. These sampling effects are best quantified by assembling and analyzing large numbers of locality-specific biotic inventories. Here, we introduce a new database of this kind for the Phanerozoic fossil record of marine invertebrates. We apply four substantially distinct analytical methods that estimate taxonomic diversity by quantifying and correcting for variation through time in the number and nature of inventories. Variation introduced by the use of two dramatically different counting protocols also is explored. We present sampling-standardized diversity estimates for two long intervals that sum to 300 Myr (Middle Ordovician-Carboniferous; Late Jurassic-Paleogene). Our new curves differ considerably from traditional, synoptic curves. For example, some of them imply unexpectedly low late Cretaceous and early Tertiary diversity levels. However, such factors as the current emphasis in the database on North America and Europe still obscure our view of the global history of marine biodiversity. These limitations will be addressed as the database and methods are refined.

Characterization of three infectious bronchitis virus isolates from China associated with proventriculus in vaccinated chickens

Outbreaks of an avian disease in infectious bronchitis-vaccinated chickens in China have led to the characterization of coronaviral isolates Q1, J2, and T3, which were isolated from proventricular tissues of the affected young layer flocks. Serologic analysis revealed that they could induce high titers of infectious bronchitis virus (IBV) antibodies in inoculated specific-pathogen-free (SPF) chickens in indirect enzyme-linked immunosorbent assay but were not neutralized by antisera specific to the IBV serotype M41 and the Australian T strain. In a pathogenicity experiment, the clinical signs and related gross lesions resembling those of field outbreaks were reproduced in SPF chickens, and viruses were reisolated from the damaged tissues, including trachea, proventriculus, duodenum, and cecal tonsil. Sequence data demonstrated the complete S1 amino acid sequences of these isolates were almost identical despite recovery from geographically different areas in China and had 47.3%-82.3% similarity in comparison with the 47 published S1 sequences. On the basis of genotyping and limited serology, the three isolates, which were responsible for field outbreaks of the disease, might be a new IBV variant.

Detection and screening of Salmonella enteritidis-infected chickens with recombinant flagellin

Screening and identification of Salmonella enteritidis in commercial poultry flocks have assumed principal roles in preventing transmission of this pathogen to humans from hen eggs. Serologic diagnosis of S. enteritidis infection in commercial flocks currently relies on laboratory-based tests for detection of antibodies to the lipopolysaccharide, whole flagella, and bacteria. We amplified a sequence from the g,m flagellin of S. enteritidis, followed by cloning, expression, and purification of the protein. The recombinant protein was first characterized by western blot and subsequently evaluated as enzyme-linked immunosorbent assay (ELISA) antigen for detection of S. enteritidis infection. A total number of 49 positive sera and 40 negative sera were tested for ELISA validation. A cutoff value of 0.14 was shown to be sufficient to discriminate the negative and positive sera. Results obtained by testing sera raised against different bacterial strains/serotypes further confirmed that this recombinant flagellin-based ELISA was indeed specific for the detection of S. enteritidis. Both sensitivity and specificity of the developed ELISA test were comparable with a commercially available test, indicating that it is a highly promising and reliable diagnostic tool for S. enteritidis infection.